In most areas of the U.S., ants are the most invasive indoor pests. In Florida and elsewhere in the Sun Belt, ant pressure is even higher. Successful baiting plays a major role in an ant prevention program by maximizing ant management in and around a customer’s home, thereby minimizing return visits. Knowledge about behavior and biology of local pest ants is key in developing a baiting program. After a PCO has knowledge about local pest ants, a prevention plan can be developed.
Every ant colony is in a different state of development. Each colony has specific needs — energy for foragers, proteins for larvae and for the queen. As changes occur in their sheltered nest, changes in necessities occur. A foraging trail of ants can suddenly change priorities when clouds turn to rain. As the water begins to enter the nest, top priority may be given to care of the larvae and pupae by moving them to a drier area.
When colony buildup occurs in the spring, workers may suddenly drop foraging for honeydew/carbohydrates in lieu of a dead insect and start to bring small bits of the insect to hungry larvae. Depending on the size and nutritional needs of the colony, the nearby environmental changes and the changing availability of food, foraging ants will often adjust their feeding preferences. Use of residuals or dusts can leave residual barriers that may exclude or redirect the ants. When an ant colony cannot be located, and sealing the ants out of a structure is not effective or feasible, baiting becomes an attractive elimination technique.
Typical commercial ant baits include liquid bait that can be placed into feeding stations or pre-baited stations already prepared for instant placement, gels in tubes to be injected into stations or onto surfaces for ants to feed upon, and granular baits to be sprinkled near foraging ants. Many of these baits are useful in eliminating hidden colonies.
Even after combining baiting with other strategies in an IPM program, PCOs may still face returning ant trails. So what can be tried when all else fails? Effective baiting may take a lot of work, but when success is achieved, baiting remains one of the most effective and environmentally responsible methods of ant management. Baiting techniques discussed in this article use EPA-registered products per label directions. In no circumstances should materials be mixed or used inconsistently with label directions.
TIPS AND TRICKS. The following five examples illustrate techniques to enhance traditional baiting programs:
1. Use of water to thin liquid baits so they can be applied by misting. Once they are placed, liquid baits dry up and slowly increase in toxicity. This occurs faster in the sun and during the summer. To slow this process, pest management professionals can use water to thin the bait or to re-wet bait placements. This is legal with Uncle Albert’s, Terro II and some other liquid baits. Cutting the bait with water and applying it with a mist applicator allows pest management professionals to apply many smaller bait placements on a surface for more access to the foragers. As water evaporates from the thinned bait, the bait returns to normal consistency. This enhances the application by prolonging the availability of fresh bait. It also allows more time for bait to be built up within the colony for a higher probability of colony elimination. (See photo at bottom left.)
2. Liquid bait placed into "feeding vials" or bait stations along foraging trails. When liquid bait is used to attract a target ant, empty plastic, tamper-resistant ant stations can be used to house the bait. This prolongs the bait from drying out and still allows ant entry. Some of these stations have a thin paper or foam film that allow the ants to suck from above without slipping into the liquid. In others the ants can approach and drink the liquid directly. In many of these stations the ants still manage to fall into the liquid bait and drown. Large numbers of dead or dying ants in these stations may release a warning pheromone and chase the rest of the workers away. We have documented this occurrence with Florida carpenter ants and Argentine ants. A better idea is to place the liquid bait in a thin vial plugged tightly with a small slice of a normal cellulose kitchen sponge. The sponge will soak up the bait slowly and allow any number of ants to gain feeding access on the surface without drowning. (See photo above.)
3. Use of multiple baits. Strategic placement of multiple-baits and feeding sites on the perimeter of the structure can provide results against one or more species of ants. Since ant feeding preferences change, through habit or need, why not give them a choice? (See photo at right.) This is not suggesting that baits be mixed (which labels do not allow), but rather be placed side by side in a group together in outdoor areas around the foundation where ant activity/trailing exists. Examples are the bases of exterior plants and trees, near log piles, trash or inside of rodent stations. Some brands of ant bait stations have two or more compartments for baits to inject or to place together. Pre-baiting with different brands and food formulas of bait to discover which is currently most attractive to ants in the neighborhood and then placing just the most attractive materials next to each other allows you to make responsible applications using only the amounts of material required. Since ant colonies typically forage over wide ranges, placing multiple bait placements around the structure will enhance results over the long run. A single bait placement might reduce the population of one colony only to have the activity/foraging be replaced by ants from another colony. The numbers of placements and range away from the structure will vary depending on the ant species encountered.
4. Bait away from the structure to reduce foraging pressure on or within the structure. Ants that nest in plants (such as white-footed ants and carpenter ants) will travel down a tree trunk and across to the foundation to enter a home. Placing bait (natural or commercial) at the base or directly on the trunk to create a feeding site will help to develop a pheromone trail away from the structure. Baiting alone around the yard might be enough to draw the ants away from the home. The key is to prevent the ants from feeding up at the house and draw them to a source away from the structure. (See photo on page 94.)
5. Bait-n-switch. In situations where baits are being consumed but ant populations remain high, extra time will be required to make an impact. Liquids in most commercial baits begin to evaporate as soon as they are placed. Evaporation of the bait increases the potency of the bait as the ants continue to forage. The number of ants that die within the colony starts rising. The colony senses that something is wrong and foraging becomes restricted. A second protective stage is budding where the colony divides and locates elsewhere to obtain other available food sources. You return to find the bait gone and just as many ants. The response to this is to take time to determine which commercial bait and pre-bait food the ants prefer. Pre-baits should match the food ingredients in the manufactured products: sweets (sugary liquids or gels), proteins (paste stations/granules/liver based, etc.) or lipids (yellow oily baits). (See photo at right.)
After observing ants feeding on an existing bait placement, remove the commercial bait and replace it with the pre-bait product in its place. Once large trails are formed, switch the bait back to the initially preferred commercial bait. Place two to three times as much pre-bait and active bait as usual. A larger share of the colony will be impacted due to the numbers of ants drawn to the food source, the size of the food source and the intensity of the pheromone trail. Even if ants begin to die, a large part of the worker population has committed to collecting the commercial bait.
CONCLUSION. The techniques illustrated here have proven successful in enhancing our company’s ant baiting programs. These are only a few of the many baiting tactics that can be used. I would enjoy discussing baiting stories, comments or questions.
The author is training and technical director, pest prevention, for Massey Services, Maitland, Fla. He can be reached at bbelmont@pctonline.com.